Experts Alert Nasa About Shuttle Hazards

WASHINGTON — NASA is focusing too closely on how individual shuttle parts might fail and does not fully understand all the hazards associated with launching the shuttle, an expert panel warned Friday.

The agency's lack of coordination among safety groups and review boards has given managers ''a fragmented picture of the safety and reliability of the total space transportation system,'' reported the National Research Council in a 14-month independent review of shuttle improvements.

''We believe NASA can make substantial further progress in providing the maximum protection for our astronauts'' by improving its understanding of shuttle hazards and statistically ranking the danger of critical parts, said retired Gen. Alton Slay, head of the 12-member panel formed by the Challenger Presidential Commission.

However, NRC panel members emphasized that their study uncovered ''absolutely no showstoppers'' that would prevent NASA from launching the shuttle safely on Aug. 4, as now planned.

''We're all quite comfortable with what has been done in preparation for the next flight,'' said panel member Bill Lenoir, a former astronaut who flew on the fifth shuttle mission.

NASA managers have worked closely with the panel during its study and ''are well on our way to addressing many of their comments and recommendations,'' agency administrator James Fletcher said in a prepared statement.

The interaction of certain parts could lead to a failure, and the weather, human mistakes and many other factors could contribute. NASA should broaden its assessment of risks to adequately take into account how all these factors affect one another, the panel said.

NASA managers are performing a risk assessment, but the panel recommended a more thorough approach that would rank the risks so top managers could monitor and try to reduce the most dangerous ones first.

''While NASA has the basic organizational elements for assessing and managing risks, the arrangement is a complex mosaic of numerous review boards and safety organizations'' that is unwieldy to manage, the panel said.

The review board also said NASA should use statistical techniques to rank the danger of individual critical parts -- called Criticality 1 and Criticality 1R items -- that could destroy the shuttle and kill the crew if they failed.

The panel noted that during the 24 missions before Challenger, 51 Criticality 1 items failed without a catastrophe. Such evidence indicates the danger of all criticality parts isn't necessarily the same.

Since NASA tightened ground rules after the Challenger accident, the number of criticality items in the two categories has increased from 2,369 to 4,686. Having so many threatening parts makes a statistical ranking even more crucial, the panel said.

NASA now ranks the danger of parts into nine general categories based on test results and other data and engineers' judgment.

The agency has been reluctant to assign statistical odds of failure to each part because engineers believe that the statistics won't be reliable without more tests.

However, with the panel's prior encouragement, NASA has conducted a statistical analysis of parts of the external fuel tank and the shuttles' auxiliary power units. The agency has promised to continue the process as shuttle flights resume until the critical parts are ranked, Slay said.

Panel members said that if their recommended improvements had been in place before the Challenger accident, managers ''would have had more information at their fingertips,'' possibly compelling them not to launch.

Even if all the improvements are not in place for the next launch, NASA should be able to proceed safely because it plans a very conservative mission, Slay said. The launch and weather conditions will be strictly limited and a satellite payload of the same type as Discovery's has been flown before.

Among the panel's other comments and recommendations:

-- NASA faces a continuing problem of shuttle booster insulation coming unglued in places and other damage during transportation to Kennedy Space Center. NASA should develop inspection techniques that can be used as late as possible in the booster stacking process to avoid trouble, the panel said.

Several segments of Discovery's boosters have had problems with peeling insulation near the joints, but NASA engineers say the problems are minor and that all the damaged areas have been fixed.

-- An average of two launch requirements are waived by NASA for each launch. The panel recommended that NASA establish a list of mandatory launch rules that can't be waived by anyone.

-- The cannibalization of parts from one shuttle to supply another -- a practice common before the Challenger accident -- introduces ''a variety of failure potentials associated with human error,'' the report said.